The present invention relates to a method for making polycarbonates having terminal functionalized radicals, such as amine or vinyl radicals, and to the products obtained therefrom. More particularly, the present invention relates to the reaction of hydroxy terminated polycarbonates with reagents such as isatoic anhydride or an acrylic acid halide.
Although polycarbonates, such as polycarbonates obtained by using 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A), have been used in a variety of applications requiring high impact strength, it has generally been recognized that polycarbonates are often deficient in specific properties which curtails their use in particular instances. For example, the use of polycarbonates in automotive applications is limited because they have poor organic solvent resistance. As shown by U.S. Pat. No. 4,732,934, it is sometimes advantageous to functionalize polycarbonates so that blends of polycarbonates with other polymers, such as polyamides, can result in a product possessing improved properties over the respective components in the blend.
A convenient method for functionalizing polycarbonates is to start with polycarbonates having terminal hydroxy radicals which can be made by the procedure of Hathaway et al, U.S. Pat. No. 4,736,013 which is incorporated herein by reference. A dihydric phenol such as bisphenol A is phosgenated in the presence of a monotetrahydropyranyl ether salt of a dihydric phenol as a chain terminator. The hydroxy terminated polymer is then obtained by cleaving the tetrahydropyranyl group with oxalic acid or a hydrogen halide acid. Functionalization of the polycarbonate can be achieved by reacting the hydroxy terminated polycarbonate with a reagent such as trimellitic anhydride.